A diminutive avian species residing in Indonesia’s Babar Islands, nestled within the Banda Sea, has been formally recognized as a distinct species following the discovery by two ornithologists that its unique vocalizations differentiate it from its closest kin. This bird, christened the cheerful fantail (Rhipidura laguceria), was hitherto considered identical to the cinnamon-tailed fantail (Rhipidura fuscorufa), which is located 135 kilometers (84 miles) to the east on the Tanimbar Islands.
The cheerful fantail (Rhipidura laguceria) in November 2022. Image credit: James A. Eaton.
The Rhipidura fuscorufa is a small, insectivorous songbird belonging to the fantail family, Rhipiduridae.
This particular species measures approximately 18 centimeters (7 inches) in length and is characterized by its cinnamon-hued tail and ventral plumage, in addition to the characteristic fanning of its tail, a behavior typical of fantails.
First documented in 1883, Rhipidura fuscorufa originated from the Tanimbar Islands.
Avian specimens from Babar, situated roughly 135 kilometers westward, were subsequently procured and analyzed by ornithologists, who arrived at the conclusion that they belonged to the same species. This consensus largely persisted for over 120 years.
“The range of Rhipidura fuscorufa is confined to Indonesia, encompassing the Tanimbar and Babar island groups,” stated Dr. James Eaton of Birdtour Asia Limited and Dr. Alex Berryman from BirdLife International.
“It was initially identified as a novel species in 1883 based on a collection of specimens gathered from the Tanimbar Islands.”
“Fifteen years later, specimens of Rhipidura fuscorufa were also obtained from Babar — the principal island within the Babar archipelago and the sole location subject to specimen collection — however, upon re-examining the material in 1901, scientists determined the specimens to be: ‘consistent with specimens from the Tanimbar Islands.’”
“For the subsequent approximately 120 years, the prevailing taxonomic classification within global and regional reference works has been to regard Rhipidura fuscorufa as a monotypic species.”
Dr. Eaton initially observed divergences between the Babar and Tanimbar populations during a visitation to Babar Island in 2011. He subsequently documented that the distinct vocal patterns strongly suggested the existence of an as-yet-undiscovered species.
To conduct a thorough investigation, the authors scrutinised 19 museum specimens housed at the American Museum of Natural History in New York and the Natural History Museum at Tring in England, alongside an analysis of 18 audio recordings originating from both island archipelagos.
They identified only minor morphological disparities: individuals from Babar tended to exhibit darker dorsal plumage and less extensive cinnamon-colored feathering on their undersides compared to their Tanimbar counterparts. Nevertheless, biometric measurements of wings, tails, beaks, and legs revealed no statistically significant variations.
However, the birds’ songs, according to the investigative team, presented a markedly different narrative.
“The vocalizations of the two Rhipidura fuscorufa populations exhibit considerable divergence,” the researchers articulated.
“The song of birds from Babar typically comprises a sequence of solitary whistles that ascend in pitch towards their conclusion. Conversely, the song of Tanimbar birds generally integrates very brief with extended whistles, resulting in a more pronouncedly rhythmic cadence, with pitch fluctuations that ascend and descend.”
“While the duration of strophes from the Tanimbar and Babar birds is comparable, those from the Tanimbar individuals contain a considerably greater number of notes, which, on average, are shorter and separated by briefer intervals.”
The cinnamon-tailed fantail (Rhipidura fuscorufa) in November 2022. Image credit: James A. Eaton.
Subsequently, the scientists executed 132 playback experiments over several years during their recreational excursions to Yamdena (Tanimbar Islands) and Babar.
Birds from both archipelagos consistently responded to playback recordings of their own population’s songs but demonstrated indifference towards recordings from the other island.
The study indicates that not a single Babar bird reacted to Tanimbar songs, nor did any Tanimbar bird respond to Babar songs.
“Despite their current classification as monotypic, our data reveal distinct differences between the Tanimbar and Babar populations of Rhipidura fuscorufa,” the researchers affirmed.
“Morphologically, the two populations exhibit subtle distinctions in dorsal coloration, and vocally, they are markedly divergent. Compelling evidence from playback experiments suggests that these song discrepancies are sufficiently pronounced to establish a premating reproductive barrier.”
“Based on these findings, we propose that the populations of Rhipidura fuscorufa inhabiting Babar warrant taxonomic separation from those found in the Tanimbar Islands.”
“We are presently unaware of an existing designation for the Babar population, and thus, we describe it as Rhipidura laguceria.”
Both the newly identified Rhipidura laguceria and its Tanimbar relative are, at present, categorized as Least Concern according to conservation assessments. These are adaptable avians that flourish in disturbed and transitional habitats rather than dense, closed-canopy forests.
“Rhipidura fuscorufa is currently listed as Least Concern on the IUCN Red List,” the scientists noted.
“Post-division, Rhipidura fuscorufa and Rhipidura laguceria will naturally possess significantly smaller geographic ranges, which align with the preliminary criteria for classification as threatened under Criteria B1 and B2 of the IUCN Red List.”
“However, both species demonstrate a high degree of tolerance for habitat degradation and are commonly observed in edge environments, cleared areas, glades, and scrubland interspersed with mature mango trees.”
“Indeed, both fantail species appear to favor heavily altered landscapes and avoid dense, closed-canopy forests.”
“Consequently, neither species meets any of the subcriteria for classification under B1 or B2, and as such, they should continue to be classified as Least Concern.”
The formal description of Rhipidura laguceria is detailed in a publication released this month in the Bulletin of the British Ornithologists’ Club.
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James A. Eaton & Alex J. Berryman. 2026. A new and cryptic fantail species from the Babar Islands, Maluku Province, Indonesia. Bulletin of the British Ornithologists’ Club 146 (2): 203-215; doi: 10.25226/bboc.v146i2.2026.a6
